Mitral valve annuloplasty ring having a posterior bow

ABSTRACT

A mitral heart valve annuloplasty ring having a posterior bow that conforms to an abnormal posterior aspect of the mitral annulus. The ring may be generally oval having a major axis and a minor axis, wherein the posterior bow may be centered along the minor axis or offset in a posterior section. The ring may be substantially planar, or may include upward bows on either side of the posterior bow. The ring may include a ring body surrounded by a suture-permeable fabric sheath formed of a plurality of concentric ring elements or bands. The posterior bow is stiff enough to withstand deformation once implanted and subjected to normal physiologic stresses. A method of repairing an abnormal mitral heart valve annulus having a depressed posterior aspect includes providing a ring with a posterior bow and implanting the ring to support the annulus without unduly stressing the attachment sutures.

RELATED APPLICATIONS

The present application is a continuation-in-part of Ser. No.10/192,516, filed Jul. 8, 2002, now U.S. Pat No. 6,858,039 , which isincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to medical devices, specificallyto an annuloplasty ring and related procedure for surgicallyreconstructing the mitral valve annulus of a patient's heart. Morespecifically, this invention relates to a mitral valve repair device andcorresponding technique that conforms to an abnormal annulus in thepathology encountered with functional mitral regurgitation having aposterior aspect depressed below the anterior aspect.

BACKGROUND OF THE INVENTION

In the anatomy of the human heart, the left atrium receives oxygenatedblood from the lungs through the pulmonary vein. The mitral valveseparates the left atrium from the left ventricle. During diastole, asthe contraction triggered by the sinoatrial node progresses through theatria, oxygenated blood passes through the mitral valve into the leftventricle. In this phase, the aortic valve leading into the ascendingaorta closes, allowing the left ventricle to fill with blood. A similarflow of venous blood occurs from the right atrium through the pulmonaryvalve to the right ventricle. Once the ventricles are full, theycontract during the systolic phase and pump blood out of the heart.During systole, the mitral valve closes and the aortic valve opens, thuspreventing blood from regurgitating into the left atrium and forcingblood into the aorta, and from there throughout the body. Because of thehigh pressures associated with the left ventricle during systole, properfunctioning of the mitral valve to prevent blood from flowing backthrough the system is extremely important.

The various anatomical components of the left ventricle LV and mitralvalve MV are depicted in FIG. 1 as seen in vertical cross-section alongan anterior-posterior plane. The mitral annulus MA comprises a fibrousring encircling the orifice between the left atrium LA and the leftventricle LV. The average human mitral annular cross-sectional area is5-11 cm². The anterior aspect of the mitral annulus MA forms a part ofthe “cardiac skeleton” and includes left and right fibrous trigones, LTand RT. FIG. 3 illustrates the mitral valve from the left atrium asexposed during surgery. The mitral valve is a bicuspid valve having aposterior leaflet PL that cooperates with an anterior leaflet AL. Theleft trigone LT and right trigone RT are indicated at the junctionpoints of the anterior leaflet AL and posterior leaflet PL. Thesejunction points are also known as commissures between the leaflets. Theposterior aspect of the mitral annulus MA, in contrast to the anterioraspect, consists mainly of muscular tissue of the outer wall of theheart.

With reference again to FIG. 1, a pair of papillary muscles P₁ and P₂attach to the lower portion of the interior wall of the left ventricleLV. Chordae tendineae CT extend between and link the papillary musclesP₁ and P₂ and free edges of the anterior and posterior leaflets AL andPL. The chordae tendineae are string-like in appearance and aresometimes referred to as “heart strings.” Although not shown in thedrawing, chordae tendoneae CT extend between each of the papillarymuscles P₁ and P₂ and both leaflets. Contraction of the papillarymuscles P₁ and P₂ pulls the chordae tendoneae CT, which in turn pullsthe leaflets open, and when the muscles relax the chordae tendonaebecome slack, allowing the leaflets to come together or “coapt.” As seenin FIG. 1, the leaflets coapt along a substantial surface area in thenormal functioning heart, with the free edges of the leaflets mutuallybending toward the left ventricle LV.

As seen in FIG. 1, and for purpose of discussion, the mitral annulus MAof a normal, healthy heart lies generally in a datum plane 20 definedperpendicular to the average blood flow direction 22 through the mitralvalve MV. Although a typical mitral annulus MA may be three-dimensional,the datum plane 20 is representative of the relative positions of theanterior and posterior sides of the annulus.

In many developed countries, congestive heart failure is a leading causeof hospitalization and death, and its incidence is increasing. Whenimperfections in the mitral valve allows blood to flow backward into theleft atrium, known as secondary mitral regurgitation, the left ventriclemust pump progressively harder to circulate blood throughout the body,which in turn promotes congestive heart failure. Heart transplantationis considered a standard treatment for select patients with severecongestive heart failure and end-stage heart disease, but only a smallnumber of donor hearts are available and there are severe surgical risksfor weaker patients. Accordingly, alternative medical and surgicalstrategies are evolving to treat such conditions.

One typical cause of mitral regurgitation is malformation of the mitralannulus MA along the more flexible posterior aspect of the annulus. Asseen in FIG. 2, some patients experience a depression h of the posterioraspect of the annulus caused by dilation of the left ventricle LV.Dilation of the left ventricle LV is a symptom associated with mitralregurgitation in patients with iopathic dilated cardiomyopathy orischemic cardiomyopathy, and in patients with long-standing valvularregurgitation from other etiologies such as myxomatous disease,endocarditis, congenital defects, or rheumatic valvular disease. FIG. 3illustrates the subsequent loss of coaptation between the posterior andanterior leaflets AL and PL from this posterior aspect depression, asseen from above.

As seen in FIG. 2, dilation of the left ventricle LV generally increasesthe distance between the papillary muscles P₁ and P₂ and the mitralannulus MA. This in turn increases the tension in the chordae tendonaeCT. The droop or depression of the posterior aspect of the annulus belowthe datum plane 20 by the distance h in combination with the increasedtension in the chordae reduces the ability of the leaflets to cometogether during systole.

Various interventions have been used to alter the size of theregurgitant orifice area. Annuloplasty rings have been developed invarious shapes and configurations over the years to correct mitralregurgitation and other conditions which reduce the functioning of thevalve. For example, Carpentier, et al. in U.S. Pat. No. 4,055,861disclosed two semi-rigid supports for heart valves, one of which beingclosed (or D-shaped) and the other being open (or C-shaped). In theclosed configuration, the ring is generally symmetric about ananterior-posterior plane, and has a convex posterior side and agenerally straight anterior side. U.S. Pat. Nos. 5,104,407, 5,201,880,and 5,607,471 all disclose closed annuloplasty rings that are bowedslightly upward on their anterior side. Because the anterior aspect ofthe mitral annulus MA is fibrous and thus relatively inflexible (atleast in comparison to the posterior aspect), the upward curve in theanterior side of each ring conforms that ring more closely to theanatomical contour of the mitral annulus, and thus reduces unduedeformation of the annulus.

In general, conventional annuloplasty rings are intended to restore theoriginal configuration of the mitral annulus MA, or in other words bringthe annulus as close as possible back to the datum plane 20 as seen inFIG. 1. When correcting a condition as seen in FIG. 2, high stresses arecreated in the sutures connecting the annuloplasty ring to posterioraspect of the annulus because the ring “pulls” the annulus upward. Thestresses sometimes result in the dehiscence or separation of the ringfrom the annulus at this location because the sutures pull through thetissue.

It should be noted here that correction of the aortic annulus requires amuch different ring than with a mitral annulus. For example, U.S. Pat.Nos. 5,258,021 and 6,231,602 disclose sinusoidal or so-called“scalloped” annuloplasty rings that follow the up-and-down shape of thethree cusp aortic annulus. Such rings would not be suitable forcorrecting a mitral valve deficiency.

While good results in the treatment of congestive heart failure andmitral regurgitation have been obtained in the preliminary applicationsof the above-described methods and apparatuses, it is believed thatthese results can be significantly improved. Specifically, it would bedesirable to produce a mitral annuloplasty ring that can reduce stressesassociated with the implantation of conventional rings.

SUMMARY OF THE INVENTION

The present invention provides an annuloplasty ring for implantation ina mitral valve annulus that has a pathologic condition such that theposterior aspect thereof droops downward abnormally. The annuloplastyring includes a rounded ring body having an anterior section and aposterior section. The ring body is oriented about a central flow axisthat defines an upward direction and a downward direction, the downwarddirection corresponding to the direction of blood flow through themitral valve annulus. The posterior section the ring body bows downwardout of a plane perpendicular to the central flow axis.

The ring body may bow downward between about 2-15 mm from one endthereof to a lowest point, and desirably bows downward between about 4-8mm from one end thereof to a lowest point. The bow in the ring body mayor may not be centered in the posterior section. Preferably, the ringbody is made of a malleable material such that the bow in the ring bodymay be manually reshaped. Desirably, the ring body is made of asemi-rigid material that will retain its posterior bow in opposition tothe stresses that will be imparted by muscles of the heart throughouteach beating cycle. The ring body may be substantially planar except inthe posterior section, or an anterior section of the ring body may bowupward from one end thereof to a lowest point.

In plan view, as seen along the flow axis, the ring body preferablydefines an oval shape with a major axis perpendicular to a minor axis,the minor axis bisecting both the anterior and posterior sections.Further, the bow in the posterior section may begin at symmetriclocations across the minor axis that are spaced from the major axisaround the ring body by an angle θ of between about 0-45°, morepreferably about 30°.

The ring body may further include two upward bows on either side of thedownward bow on the posterior section, and wherein downward bow may bebetween about 2-15 mm. In one embodiment, the ring body comprises aplurality of ring elements concentrically disposed. A polymer strip inbetween each ring element may be provided. Optionally, the ring elementscomprise bands that have a substantially larger height in the flow axisdimension than in the dimension perpendicular to the flow axis. Further,the ring elements may have varying heights so that the ring body is moreflexible in the posterior section than around the remainder of the ringbody.

Another aspect of the present invention is a method of repairing amitral heart valve annulus that has a posterior aspect that is depresseddownward along the blood flow axis relative to an anterior aspect. Themethod includes implanting an annuloplasty ring having an anteriorsection sized to fit the anterior aspect of the annulus and a posteriorsection sized to the posterior aspect, wherein the ring posteriorsection bows downward parallel to the central axis relative to theanterior section. The annuloplasty ring may be malleable and the surgeonadjusts the bow in the posterior section manually.

Another aspect of the invention is a method of repairing a mitral heartvalve annulus that has a posterior aspect, an anterior aspect, and ablood flow axis. The method includes inspecting the shape of the mitralannulus and selecting a three-dimensional annuloplasty ring based on theshape of the mitral annulus. The selected annuloplasty ring has ananterior section and a posterior section generally arranged around acentral axis. The central axis defines an upward direction and adownward direction, wherein the ring posterior section bows downward outof a plane perpendicular to the central axis. The method includesimplanting the annuloplasty ring so that the ring posterior sectionattaches to the posterior aspect of the mitral valve annulus and theposterior section bows in the blood flow direction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-section of a healthy left ventricle through the mitralvalve between the anterior and posterior leaflets;

FIG. 2 is a cross-section of a dilated left ventricle through the mitralvalve between the anterior and posterior leaflets;

FIG. 3 is an atrial view of the mitral valve of FIG. 2 exposed during asurgical procedure;

FIG. 4 is a plan view of annuloplasty ring of the present inventionimplanted so as to restore competency to the mitral valve;

FIG. 5 is a perspective view of an annuloplasty ring of the presentinvention over an abnormal mitral valve as viewed from the posteriorside;

FIG. 6 is a perspective view of the annuloplasty ring of FIG. 5 over theabnormal mitral valve as seen from the side;

FIGS. 7A-7C are plan, front, and side views of an exemplary annuloplastyring of the present invention having a posterior bow;

FIGS. 8A-8C are plan, front, and side views of an alternativeannuloplasty ring of the present invention having a posterior bowbetween two raised portions;

FIGS. 9A and 9B are front and side elevational views, respectively, ofan inner ring body of a further annuloplasty ring of the presentinvention having an off-center posterior bow and an anterior bow;

FIG. 10 is a top plan view of an inner ring body of an annuloplasty ringof the present invention showing details of a composite bandconstruction; and

FIGS. 11A-11B are plan and front views of an asymmetric annuloplastyring of the present invention having a posterior P1 bow.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The attached figures illustrate several exemplary embodiments of theannuloplasty ring of the present invention, which can be described asbeing continuous and having an anterior side, a posterior side and rightand left sides. All of the sides are generally curvilinear with nospecific demarcations to indicate abrupt transitions therebetween.Rather, smooth transitional sections between the adjacent sides providecurvilinear connections that give the ring a generally rounded (e.g.,oval) configuration.

An exemplary annuloplasty ring 30 of the present invention is shown inFIG. 4 implanted around a mitral annulus MA. As described above, themitral annulus has an anterior leaflet AL and a posterior leaflet PL.When the ring 30 is implanted, the leaflets are brought closer togetherand supported so that they meet at a coaptation surface 32. The ring 30thus corrects the problem of functional mitral regurgitation.

The ring 30 has an oval or somewhat D-shaped configuration with arelatively straight anterior section 34 opposite a curved posteriorsection 36. A pair of trigone or commissure markers 38 a, 38 b generallydelimit the anterior side 34, while a pair of opposed side sections 40a, 40 b extend between each of these markers and the posterior section36. A plurality of knotted suture loops 42 are typically used to securethe ring 30 to the mitral annulus MA, although other fasteners such asstaples, fibrin glue, or the like may be used.

In the pathological conditions for which the annuloplasty ring 30 isbest suited, the posterior aspect of the mitral annulus is depressedrelative to the anterior aspect, as is illustrated in FIG. 2. In theview of FIG. 4, the posterior aspect will be depressed into the pagerelative to the anterior aspect. The annuloplasty ring 30 of the presentinvention has a shaped posterior section 36 that generally follows themodified shape of the mitral annulus MA. In other words, the posteriorsection 36 is bowed into the page relative to the anterior section 34.When secured in place with sutures 42, for example, the ring 30 supportsthe mitral annulus MA in its modified shape, rather than trying torevert the annulus back to the original substantially planarconfiguration. At the same time, the ring 30 desirably constricts theorifice circumference defined by the annulus so as to bring the anteriorleaflet AL and posterior leaflet PL closer together. Because the ring 30does not pull the posterior aspect of the mitral annulus MA upward fromits modified position, high stresses are not set up in the attachmentsutures 42 and thus there is less potential for dehiscence.

FIGS. 5 and 6 illustrate the exemplary annuloplasty ring 30 inperspective above a mitral annulus that is depressed on its posteriorside. The bow of the ring 30 in its posterior section 36 is seen best inFIG. 6 mimicking the depression of the posterior aspect of the mitralannulus MA in the pathology encountered with functional mitralregurgitation.

The exemplary annuloplasty ring 30 of FIGS. 4-6 is shown in more detailin FIGS. 7A-7C. The ring 30 is shown complete with a fabric covering.For purpose of orientation, FIG. 7A illustrates orthogonal axes whereinthe X- and Y-axes generally define the datum plane 20 as mentioned abovewith respect to FIGS. 1 and 2. The X-axis extends across the ring 30from one side 40 a to the opposite side 40 b at the point of maximumdimension. The X-axis thus defines a major axis of the ring 30. TheY-axis defines a plane of symmetry for the ring 30 extending between amidpoint of the anterior side 34 to a midpoint of the posterior section36. The Y-axis also defines a minor axis for the ring 30.

As with many conventional rings, the ratio of the minor axis dimensionto the major axis dimension is desirably about 3:4. This size ratio isthe “classic” shape of the mitral annulus, and may be the bestconfiguration of the annuloplasty ring 30. However, it is contemplatedthat other shapes that have smaller minor axis-to-major axis ratios mayactually increase leaflet coaptation. Although not geometricallyprecise, the non-circular ring configuration may be considered oval,elliptical or D-shaped. It should be noted that the present inventioncould also take the form of a discontinuous ring that has a C-shape, forexample. The break in such a ring may be in the anterior section, andthe posterior section is continuous and exhibits the downward bow asexplained.

The Z-axis in FIG. 7B lies along of the axis of blood flow through thering 30 when implanted, and it will be understood that the positive Zdirection is the “upward” direction, the negative Z direction is the“downward” direction, and the ring 30 is designed to be implanted in amitral annulus such that blood will flow in the downward direction.

Several points are noted around the ring 30 to help describe theposterior bow. These points, and the ones shown in FIGS. 8A-8B, areimaginary center points through the cross-section of the ring 30. Twopoints A are symmetrically located on either side of the Y-axis at anangular distance θ from the X-axis. The midpoint of the posteriorsection 36 is denoted B. The ring 30 has a posterior bow such that thepoint B is at the lowest elevation along the Z-axis. The magnitude ofthis posterior bow is indicated by the dimension Z₁ in FIG. 7C. Thepoints A on either side of the posterior section 36 represent thelocation where the posterior bow begins. That is, except for theposterior section, the ring 30 is preferably substantially planar.However, the anterior section 34 can optionally be bowed upward by adistance of between about 2-4 mm (0.08-0.16 inches), as in certain ringsof the prior art. In the latter example, the posterior section 36 bowsdownward in the Z-direction relative to the elevation of the trigonemarkers 38 a, 38 b.

Various possible configurations for the ring 30 as seen in FIGS. 7A-7Care contemplated, with the dimension Z₁ and the angle θ varying betweenranges determined by the overall size of the mitral annulus, the extentof anatomical droop of the posterior aspect, and various other factorsincluding surgeon preference. Nevertheless, certain ranges are believedsuitable to support and correct a majority of the patients exhibitingthe particular anatomical irregularity as described herein. The downwardbow or posterior bow preferably extends along a majority of theposterior section 36 between the points A, which points are between 0and 45° from the X-axis (θ). More preferably, the points A are between20-40°, and more particularly about 30° from the X-axis. The magnitudeof bow Z₁ may be between about 2-15 mm (0.08-0.59 inches), and moretypically is between about 4-8 mm (0.16-0.31 inches), depending on thesize of the ring.

Although the ring 30 is shown in FIGS. 7A-7C as symmetric about theY-axis, it does not necessarily have to be so. For example, the point Bmay be displaced from the Y-axis such that the downward bow is notcentered in the posterior section 36. An asymmetric ring is shown anddescribed below with reference to FIGS. 9A and 9B.

FIGS. 8A-8C illustrate an alternative annuloplasty ring 50 of thepresent invention that has both upward and downward bows. Again, thering 50 is shown complete with a fabric covering. The ring 50 includesan anterior section 52, a posterior section 54, and a pair of sidesections (not numbered) therebetween. The ring 50 is generally planar onthe anterior section 52 and shaped on the posterior section 54. Thepoints A symmetrically disposed across the Y-axis again denote thelocations on each side where the ring 50 begins to curve out of a plane.In this embodiment, the ring curves upward in the Z-direction from thepoints A, as best seen in FIG. 8B, to high points C, and then dipsdownward to the midpoint B of the posterior section 54. The downward bowof the ring between points A and B is shown in FIG. 8C as the dimensionZ₂, which has a magnitude similar to that given for Z₁ in FIG. 7C. Theupward curve may be selected so as to better match the patient's annulusshape. Furthermore, the anterior section 52 may be upwardly bowed by adistance of between about 2-4 mm (0.08-0.16 inches).

Various permutations of the ring 50 shown in FIGS. 8A-8C arecontemplated, with the dimensions being altered based on numerousfactors. In an exemplary embodiment, the points A are desirably disposedan angular distance α from the X-axis of between about 0-15°, and moredesirably between about 5-10°. The points C of maximum height of thering 50 are preferably spaced an angular distance β from the X-axis ofbetween about 15-45°, and more preferably between about 25-35°. Thelowest point B of the ring 50 may be bowed along the Z-axis as in theembodiment of FIGS. 7A-7C, so that, as indicated FIG. 8C, Z₂ isdesirably between about 2-15 mm (0.08-0.59 inches), and more typicallyis between about 4-8 mm (0.16-0.31 inches), depending on the size of thering. Therefore, the total height of the ring 50 is at least 2 mm, andmay be greater than 15 mm.

FIGS. 9A and 9B show an inner ring body 60 for use in an annuloplastyring of the present invention. The ring body 60 has a posterior bow 62that is offset from the center of a posterior section 64. In theillustrated embodiment, the bow 62 is offset toward the posterio-medialside (to the right) by about 20% of the entire major axis width of thering body 60. Another way to state the offset is that, in plan view, thebow 62 is centered at a clock position, with 12:00 being centered in theanterior side. In that sense, the bow 62 is centered between 3:00 and6:00, and more preferably is centered at about 5:00. The axial bow Z₃ isshown and may vary from about 2.0 mm (0.08 inches) to about 4.0 mm (0.16inches), and more preferably from about 3.0 mm (0.12 inches) to about3.8 mm (0.15 inches), depending on ring size. In addition, the ring body60 has an anterior section 66 that is upwardly bowed by a distance ofbetween about 2-4 mm (0.08-0.16 inches).

The inner ring body 60 demonstrates an asymmetric ring that conforms topatients that have a posterior annular bow that is displaced from themidline. It is believed that most patients have such a malformed anatomyresulting from the pathologic conditions described herein. However,posterior bows that are centered or even offset to the left have beenobserved. Therefore, one configuration of ring that is embodied in thepresent invention is one that is pre-shaped with a posterior bow in themiddle or to the right, and that is malleable so that the bow can beexaggerated or diminished by the surgeon after examination of theprecise shape of the patient's annulus. Further, in such a convertiblering the bow can even be displaced, from the right to the left, forexample. Although the material of the ring permits manual deformation,it would be stiff enough to withstand further deformation once implantedand subjected to normal physiologic stresses.

The ring preferably includes an inner ring body and an outer sewingsheath that permits the ring body to be sutured into the mitral annulus.The sewing sheath should be sufficiently porous and/or flexible topermit sutures to be passed therethrough. One exemplary construction isto enclose the inner ring body in a tubular sheath of suture-permeablematerial, such as silicone, which is then covered with a fabric tube,such as polyethyl terapthalate.

As opposed to flexible annuloplasty rings that are designed simply toreduce the circumference of the mitral annulus, the annuloplasty ring ofthe present invention must be semi-rigid. It must retain its posteriorbow in opposition to the stresses that will be imparted by muscles ofthe heart throughout each beating cycle. For example, the ring body maybe made from materials such as Elgiloy (a cobalt-nickel alloy),titanium, or Nitinol (a nickel-titanium alloy).

FIG. 10 illustrates one exemplary construction of the inner body of theannuloplasty rings of the present invention that utilizes multiple flatbands of Elgiloy in a composite structure. Specifically, there are fourbands 70 a, 70 b, 70 c, and 70 d from the outside to the inside. Thefour bands are concentrically disposed in the shape of the ring. Eachband is a flat strip of material having a width of between about 1.4-2.0mm (0.056-0.078 inches). In one embodiment, the bands 70 overlap in theanterior section 72 of the ring body and are fastened together by, forexample, spot welding at multiple points. The width of each strip mayalso be greater in the anterior section 72 than in a posterior section74, which means that the ring body is more flexible in the posteriorsection than in any other section. Although not shown, a plurality ofstrips of protective film is used in between each band 70, and on theouter face of the outer band 70 a. The strips may be a polymer such asMylar. The strips help reduce rubbing between the bands 70 and alsodeflect suture needles from the outer band 70 a and thus preventscratching thereto.

A still further alternative annuloplasty ring 80 is shown in FIGS.11A-11B with a fabric covering. As before, FIG. 11A illustratesorthogonal axes wherein the X- and Y-axes generally define the datumplane 20 as mentioned above with respect to FIGS. 1 and 2. The X-axisextends across the ring 80 from one side 82 a to the opposite side 82 bat the point of maximum dimension. The X-axis thus defines a major axisof the ring 80. The Y-axis extends between a midpoint of an anteriorside 84 to a midpoint of a posterior side 86 and defines a minor axisfor the ring 80. The posterior side 86 extends around the lower portionas seen in FIG. 1A between a pair of trigone markers 88 a, 88 b.

The Z-axis in FIG. 11B lies along of the axis of blood flow through thering 80 when implanted, and it will be understood that the positive Zdirection is the “upward” direction, the negative Z direction is the“downward” direction, and the ring 80 is designed to be implanted in amitral annulus such that blood will flow in the downward direction. Anoutline of the annuloplasty ring 80 in plan view is superimposed on theelevational view of FIG. 1B for a better understanding of the shape.

As seen in plan view of FIG. 11A, the ring 80 has an asymmetric shape onits posterior side 86. For purposes of illustration, the posterior side86 may be divided into sections P1, P2, and P3 as shown. The nativeposterior leaflet is divided into three scallops in sequence startingfrom the anterolateral trigone and continuing in a counterclockwisedirection to the opposite trigone, and the ring sections P1, P2, P3,generally correspond to these scallops. The asymmetry in the ring 80 ismanifested by an extended Y-axis dimension in the P2-P3 area, while theP1 area is preferably more conventionally shaped.

Points are noted around the ring 80 to help describe one preferredembodiment of a posterior bow 90. As in the earlier illustrations, thesepoints are imaginary center points through the cross-section of the ring80. Two points A represent the locations where the posterior bow 90begins and ends. In the illustrated embodiment, the ring 80 has aposterior bow 90 that is offset toward the P1 section, and bridges theP1-P2 sections. Alternatively, the posterior bow 90 may be locatedentirely or substantially within the P1 section. Except for the downwardbow 90, the ring 80 is preferably substantially planar, although theaforementioned upward curves as in FIGS. 8A-8C on either side of theposterior bow may be included. Also, the anterior section 84 canoptionally be bowed upward, such as, for example, by a distance ofbetween about 2-4 mm (0.08-0.16 inches), as in certain rings of theprior art. In the latter example, the posterior section 86 bows downwardin the Z-direction relative to the elevation of the trigone markers 88a, 88 b. The annuloplasty ring 80 is particularly useful for repairingpathologies associated with ischemic cardiomyopathy and anteriorinfarct.

It will also be readily apparent that supporting the mitral valveannulus with the present annuloplasty ring will maintain the posteriorleaflet depressed below the anterior leaflet, and thus the area ofcoaptation therebetween will be different than in a healthy valve. Thisis required by the pathology of the ventricle with displacement of thepapillary muscles and posterior leaflet. However, those of skill in theart will recognize that this slight realignment of the leaflets isacceptable because of the surplus area of the leaflets available forcoaptation, and because the realignment will be offset by other changesto the shape of the annulus that should over time improve coaptation ofthe two leaflets and therefore decrease regurgitation.

It will also be appreciated by those of skill in the relevant art thatvarious modifications or changes may be made to the examples andembodiments of the invention described in this provisional application,without departing from the intended spirit and scope of the invention.In this regard, the particular embodiments of the invention describedherein are to be understood as examples of the broader inventive conceptdisclosed in this application.

1. An annuloplasty ring for implantation in a mitral valve annulus, saidannuloplasty ring comprising: a rounded ring body having an anteriorsection adapted to be implanted on the anterior aspect of the mitralvalve annulus and a posterior section adapted to be implanted on theposterior aspect of the mitral valve annulus; wherein the ring body isoriented about a central flow axis, the flow axis defining an upwarddirection and a downward direction, the downward direction correspondingto the direction of blood flow through the mitral valve annulus, andwherein the ring body as viewed downward in plan view has a continuousD-shaped configuration with the anterior section being relativelystraight and the posterior section being outwardly curved; wherein thering body is substantially planar except in the posterior section; and,wherein in the posterior section the ring body bows downward out of aplane perpendicular to the central flow axis, and wherein the downwardbow is substantially centered in the posterior section and exhibitssmooth curvilinear transitions to adjacent ring body sections.
 2. Theannuloplasty ring of claim 1, wherein, in the posterior section, thering body bows downward between about 4-8 mm as measured along the flowaxis from a point around the ring body at which the downward bow beginsto a lowest point of the downward bow.
 3. The annuloplasty ring of claim1, wherein the ring body is made of a malleable material such that thebow in the ring body may be manually reshaped.
 4. The annuloplasty ringof claim 1, wherein the ring body is made of a semi-rigid material thatwill retain its posterior bow in opposition to the stresses that will beimparted by muscles of the heart throughout each beating cycle.
 5. Theannuloplasty ring of claim 1, wherein in plan view as seen along theflow axis of the ring body generally defines an oval shape with a majoraxis perpendicular to a minor axis, wherein the minor axis bisects boththe anterior and posterior sections, and wherein the bow in theposterior section begins at symmetric locations across the minor axisthat are spaced from the major axis around the ring body by an angle θof between about 0-45°.
 6. The annuloplasty ring of claim 1, wherein thering body further includes two upward bows on either side of thedownward bow in the posterior section.
 7. The annuloplasty ring of claim6, wherein the ring body bows downward between about 2-15 mm as measuredalong the flow axis from a point around the ring body at which either ofthe upward bows begins to a lowest point of the downward bow.
 8. Theannuloplasty ring of claim 6, wherein in plan view as seen along theflow axis of the ring body generally defines an oval shape with a majoraxis perpendicular to a minor axis, wherein the minor axis bisects boththe anterior and posterior sections, and wherein the upward bow beginsat symmetric locations across the minor axis that are spaced from themajor axis around the ring body by an angle α of between about 0-15°. 9.The annuloplasty ring of claim 1, wherein the ring body comprises aplurality of ring elements concentrically disposed.
 10. An annuloplastyring for implantation in a mitral valve annulus, said annuloplasty ringcomprising: a rounded ring body having an anterior section adapted to beimplanted on the anterior aspect of the mitral valve annulus and aposterior section adapted to be implanted on the posterior aspect of themitral valve annulus, the posterior section being divided intosubsections P1, P2, and P3 as seen in plan view in series from ananteriolateral trigone in a counterclockwise direction; wherein the ringbody is oriented about a central flow axis, the flow axis defining anupward direction and a downward direction, the downward directioncorresponding to the direction of blood flow through the mitral valveannulus, and wherein the ring body as viewed downward in plan view has acontinuous D-shaped configuration with the anterior section beingrelatively straight and the posterior section being outwardly curved;wherein in the posterior section the ring body bows downward out of aplane perpendicular to the central flow axis, wherein the bow in thering body is off-center in the posterior section toward the P1 section;and wherein the ring body further includes two upward bows on eitherside of the downward bow in the posterior section.
 11. The annuloplastyring of claim 10, wherein the ring body bows downward between about 4-8mm.
 12. The annuloplasty ring of claim 10, wherein, in the posteriorsection, the ring body bows downward between about 2-15 mm as measuredalong the flow axis from a point around the ring body at which either ofthe upward bows begins to a lowest point of the downward bow.
 13. Theannuloplasty ring of claim 10, wherein the ring body is made of amalleable material such that the bows in the ring body may be manuallyreshaped.
 14. The annuloplasty ring of claim 10, wherein the ring bodyis made of a semi-rigid material that will retain its posterior bow inopposition to the stresses that will be imparted by muscles of the heartthroughout each beating cycle.
 15. The annuloplasty ring of claim 10,wherein the ring body comprises a plurality of ring elementsconcentrically disposed.
 16. The annuloplasty ring of claim 10, whereinthe downward bow in the ring body is wholly located within the P1section.